In 2010, while peeling back the layers of Hialeah’s “shadow banking’’ industry, federal prosecutors pressed the city’s mayor about allegations that he had collected exorbitant cash interest payments on more than $1 million in loans he made to friends and acquaintances. Julio Robaina’s answer? Not true.On Thursday, Robaina’s words came back to haunt him, when a federal grand jury indicted him and his wife on charges of conspiring to evade income taxes, making loans at sky-high interest rates, failing to report secret cash payments — and lying to federal authorities. He made the statements at issue in August 2010, while preparing an unsuccessful run to become Miami-Dade County mayor.Robaina, 47, and his wife Raiza Villacis Robaina, 39, who operated two loan companies, are accused of receiving the undisclosed cash payments as interest on the personal loans they made to friends, including convicted Ponzi schemer Luis Felipe Perez. The loans were doled out as part of an informal banking system operating below the radar in Hialeah. Husband and wife, scheduled to surrender to authorities and have their initial court appearance Friday, proclaimed their innocence through Julio Robaina’s defense attorney.In addition to tax evasion, both Robainas were indicted on charges of filing false tax returns that understated their income. According to an indictment, the couple’s reported income swung wildly from a loss of $62,015 in 2006 to a gain of $1,023, 672 in 2007, when they knew their “total income was greater than reported” in both years.The indictment also accused the couple of lying to federal agents. Robaina is charged with making a “false statement” in August 2010, when he told IRS agents that he had “no involvement” in his wife’s loan businesses, MR Holdings and RVR Holdings, when the defendant knew “he had negotiated and agreed to the terms of the loans made” by those companies, the document states.